A new generation of hybrid tandem mass spectrometers combines quadrupole (Q) and time of flight (TOF) mass analyzers to provide very high performance in terms of sensitivity, resolution and-mass measurement accuracy. We are working with Perkin Elmer-Sciex of Toronto, Canada to evaluate the performance of an instrument of this type for use in the UCSF Mass Spectrometry Facility. A wide range of samples is being investigated, including peptides from protein digests; phospho, sulfo and glycopeptides, and lipooligosaccharides, in positive and negative ionization modes. This evaluation is important for decisions that need to be made concerning future equipment purchases for the Mass Spectrometry Facility. It is also beneficial to the manufacturers as they obtain input and feedback on this innovative instrument.